Theoretically, such a tab is possible, but I really doubt this is the case.
More likely what you have is a 20mcg tab (with the person offering this to you being mistaken as to the correct dosage). A 200mcg tab would be way too strong. You will know pretty soon if the tab is really 200mcg - symptoms from a dosage of this amount are likley to include sweating, shaking and jitteriness, increased heart rate, and not being able to sleep.